Due to the facts that production of ships adopts a make-to-production method for every single product, and double-curvature plates thereof have certain structural characteristics, a forming processing method for the double-curvature plates are different that for film plates of vehicles, which employs massive production of die stamping. At present, conventional forming methods for curvature plates of ships mainly comprises a line heating method, a cylindrical rolling method, a multi-point bending method, and so on.
The line heating method is to conduct partial and linear heating on plates via line heat source such as flame or high-frequency induction heaters based on a principle of thermal expansion and contraction, so that residual plastic deformation of a work piece appears and enables the plates to be bent and formed. During the process, water may be sprayed on heating lines for reducing temperature thereon after line heating according to requirement of ships' structure for properties of materials, whereby improving forming efficiency. However, due to relationship between temperatures and the materials properties, an actual processing temperature needs to be controlled within a certain range, which may influence forming efficiency in a condition of large curvature and thick plates. In addition, for forming of a plate with different in-plane strain and out-of plane strain on different surface at different positions thereof (such as a twisted plate), it is difficult for the line heating method to meet requirement for the forming processing.
It is obvious that the cylindrical rolling method cannot enable processing of a double-curvature shape, but a single-curvature shape. As for the multi-point bending method like a multi-point cold pressing method, since it completely relies on force applied to a plate that is to be formed, and the force and range of the force are extremely large, a problem of resisting resilience caused thereby becomes very protuberant, and total volume of corresponding equipments and construction cost thereof may be increased. Moreover, no matter cold processing or hot processing is employed in the above-mentioned methods, problems therewith, such as uncertain quality, low processing efficiency and so on, still exist since it is mainly depend on experience-based manual operation or manual control.